DIABETES AWARENESS

People with diabetes have likely heard the message about their higher-than-normal risk of developing coronary artery disease (blocked arteries) and heart attack.

Another heart problem exists that is linked to diabetes that is probably less widely known and often harder to understand – heart failure.

Heart failure can be a confusing term; the word “failure” might lead us to believe we are talking about a complete breakdown in functioning. However, heart failure is not about a heart that doesn’t work at all; the problem is that the heart becomes damaged or weakened, and less effective at moving blood throughout the muscle.

“Heart failure means the heart is failing as a pump. It’s not pumping blood properly,” says Richard Gilbert, the head of the endocrinology division at St. Michael's Hospital in Toronto, a professor of medicine at the University of Toronto, and Canada Research Chair in Diabetes Complications. “Heart failure is just as common as heart attack – and a lot more common than stroke – in people with diabetes.”

Medical professionals use the term “toxic triad” to describe the three main factors that increase the risk of heart failure in those who have diabetes, Dr. Gilbert explains.

One of the contributing factors is the fact that people with diabetes have “accelerated coronary artery disease” compared to the general population, he says. They are more likely to develop damaged arteries at an earlier age and that can lead to heart failure.

High blood pressure also increases risk of heart failure. “In people with diabetes, blood pressure often doesn’t drop as much overnight as it does in people without diabetes, so their blood pressure is higher over a 24-hour period.”

“Thirdly, there is a condition called diabetic cardiomyopathy, where the heart becomes stiff and doesn’t relax properly,” Dr. Gilbert says. “And that means pressure builds up behind it, causing a fluid leak in the lungs that leads to shortness of breath, a key symptom of heart failure.”

The good news? Patients with diabetes can use similar strategies to reduce their risk for both heart disease and heart failure. These include keeping their blood sugar at healthy levels, exercise and healthy eating, and controlling blood pressure with medication and/or lifestyle changes.

A new class of diabetes drugs recently made available in Canada offers an opportunity to also reduce these risks. Dr. Gilbert says research has shown that these medications, called SGLT2 inhibitors, are an important therapy for diabetes management that also addresses the heart failure risk.

That assessment is shared by cardiologist Kim Connelly, who also practises at St. Michael’s Hospital and is an associate professor of medicine at the University of Toronto.

“The SGLT2 inhibitors stop people from dying by reducing heart failure hospitalization. For people who end up in hospital with heart failure, approximately one quarter will not survive beyond one year,” says Dr. Connelly.

“These new drugs reduce the chance of ending up in hospital by about 35 per cent. That is a huge reduction and very exciting.”

The relationship between diabetes and heart problems is an important matter for cardiologists – who treat heart disease and heart failure – as well as for endocrinologists, who, while treating diabetes, seek to prevent heart-related complications.

About 30 to 40 per cent of all people in heart-function clinics have diabetes, says Dr. Connelly. “The risk of heart failure is increased about 25 times in diabetes patients aged 30–40 and, up to the age of 80, the risk is still doubled compared to people without diabetes.”

Both Dr. Gilbert and Dr. Connelly say collaboration between endocrinologists and cardiologists should increase on behalf of their patients with diabetes.

“This kind of interaction between the two disciplines is very important and it needs to become more common,” says Dr. Gilbert.

“We need to work together to make sure people who need these new drugs are treated, so we can prevent heart failure and save lives,” adds Dr. Connelly.